The gadget maker introduced the seventh generation of its smallest portable media player this afternoon, and much to my surprise, the dimensions grew to incorporate a larger screen.

All of Apple's products have shrunk over the years -- the iPod begets the iPod Mini begets the Nano, and so forth -- but this year they grew. Indeed, the iPhone 5 grew taller as it grew thinner, echoing past updates to the iPod Nano. (See the evolution below.)

But the Nano model has ballooned and shrunk with each new generation. It's as if it can't decide what it wants to be when it grows up.

A little history: the Nano model came into existence as the next step after the iPod Mini. Its small footprint -- thanks to flash memory -- helped it succeed in its best-use case: gym companion.

That role was challenged by the display-less iPod shuffle, which for five years satisfied gym-going folk and bargain buyers alike with a clip-ready design and a low, low price. ("Most wearable iPod ever," Apple touted during the introduction of the second generation.)

The Nano's dimensions grew with the addition of the Shuffle -- even going the short-and-squat route in 2007 -- but once that model was made obsolete in 2010, the Nano took its place: same dimensions, but with a small screen filled with iOS-sized icons. It was the perfect distillation of Apple's products: a gym-optimized iPod that kept the connected DNA of its larger siblings.

So where do you go from there? Larger, apparently. The newest iPod looks like the very first one, albeit slightly wider and almost all screen. (You can guess what's probably coming next: no buttons.)

All this back-and-forth makes me wonder what the ideal scenario is. Is the perfect Nano a tiny iPod Touch, or is it a gym-optimized device with the same capabilities? Or is the new design in fact optimal for both scenarios? (Which prompts the question, why did Apple go so small with the previous generation?) I don't have the answer, but there are few products in Apple's portfolio that have seen such drastic departure generation to generation.

Here's a look:

What do you think? Is there a vision for the iPod Nano, or is its design fate only dictated by the rest of Apple's portfolio?